1. Field of the Invention:
The present invention relates to novel compositions which are useful for the release treatment of mold walls. The present invention more especially relates to novel such compositions comprising organopolysiloxane polymers which are applied as non-stick coatings and thereby facilitate the demolding of molded shaped articles consisting of organic materials such as rubbers, resins, plastics and cellular materials.
The advantage of these organopolysiloxane polymers is that they do not interfere with the gluing, painting or varnishing of the molded final products. They also have the advantage of efficiently adhering to the materials of which the molds are made; as a result of this, a large number of demoldings can be carried out before the mold wall members need to be treated again.
2. Description of the Prior Art:
Organopolysiloxane polymers have long been used to facilitate the demolding of shaped articles made of organic materials. Despite their non-stick nature, some of these compounds allow the molded products to be subsequently painted. Same are described, in particular, in French Pat. Nos. 1,340,398, 1,448,165 and 1,499,845.
French Pat. No. 1,340,398 describes diorganopolysiloxanes consisting of 10 to 90 mole % of units of the formula (C.sub.6 H.sub.5 X)CH.sub.3 SiO and 10 to 90 mole % of units of the formula CH.sub.3 (X')SiO in which X is an alkylene radical containing 2 to 3 carbon atoms and X' an alkyl radical also containing from 2 to 3 carbon atoms.
French Pat. No. 1,448,165 relates to diorganopolysiloxanes consisting of units of the formula CH.sub.3 (Y)SiO and optionally of units of the formula CH.sub.3 (Y')SiO in which Y is an alkyl radical containing from 8 to 20 carbon atoms and Y' is an alkyl radical containing from 1 to 7 carbon atoms.
French Pat. No. 1,499,845 describes diorganopolysiloxanes consisting of units of the formula CH.sub.3 (Z)SiO and of units of the formula CH.sub.3 (Z')SiO, in which Z is an alkyl radical containing at least 7 carbon atoms and Z' is a 2-phenylethyl radical.
Another French Pat. No. 1,570,178, relates to the use, for demolding polyurethane foams, of diorganopolysiloxanes having a structure closely akin to those of the diorganopolysiloxanes above described. In fact, they consist of at least 50 mole % of units of the formula CH.sub.3 (W)SiO, at most 40 mole % of units of the formula ##STR1## or of the formula C.sub.6 H.sub.5 CH.sub.2 CH.sub.2 (CH.sub.3)SiO and at most 10 mole % of units of the formula CH.sub.3 (W')SiO, formulae in which W is an alkyl radical containing from 3 to 30 carbon atoms, W' is a methyl, ethyl, phenyl or benzyl radical, or a polyether chain; and at each end of their polymer chains they terminate in a hydroxy radical, or a triorganosiloxy moiety.
These diorganopolysiloxanes are deposited in a liquid form onto the wall members of the mold after each demolding; prior to such deposition, however, a conventional mold-release agent such as a wax, a silicone resin or a silicone rubber must be preliminarily applied thereto.
The diorganopolysiloxanes described in the aforenoted French Pat. Nos. 1,340,398, 1,448,165, 1,499,845 and 1,570,178, do not appear to interfere with the painting or gluing of the molded final products; however, they have the disadvantage of not adhering efficiently to mold walls, and as a result of this their application to these walls must be frequently renewed during the molding/demolding cycles.
Organopolysiloxanes having another structure are described in U.S. Pat. No. 2,811,408. These are copolymers consisting of (CH.sub.3).sub.3 SiO.sub.0.5 and SiO.sub.2 units, distributed such as to provide a CH.sub.3 /Si ratio of 1 to 2.5; they are optionally combined with either straight or branched chain organopolysiloxanes. The patent teaches the use of these polymers for efficient demolding of organic or organosilicone materials. It does not teach the means to be employed to ensure that the molded products can subsequently be painted.